Various types of printing units intended for price labelling machines are already known. In one type of such units, number and letter printing matrices to print various signs on e.g., price labels are arranged on the peripheries of pivotally mounted printing segments which upon operation of various actuating means may be brought to printing position. Printing units of this kind require a large number of movable components and they are space-requiring and expensive to manufacture. In another type of printing units, the printing is effected by means of rotating printing wheels. As the printing is effected during the rotation of the printing wheels the resulting text lacks clarity.